Q. Equation of the latusrectum of the ellipse $9x^{2} + 4y^{2} - 18x - 8y - 23 = 0\$ are

A) $y = \pm \sqrt{5}$
B) $y = \pm \sqrt{5}$
C) $y = 1 \pm \sqrt{5}$
D) $y = - 1 \pm \sqrt{5}$
Explanation

(c)
Given equation can be rewritten as
$\Rightarrow \ \frac{(x - 1)^{2}}{4} + \frac{(y - 1)^{2}}{9} = 1$
Also $e = \ \sqrt{1 - \frac{4}{9}} = \frac{\sqrt{5}}{3}\ \ \lbrack\because a < b\rbrack$
$\therefore$ Equations of latusrectum are
$y - 1 = \pm 3.\frac{\sqrt{5}}{3}$ [using $y = \pm be\rbrack$
$\Rightarrow y = 1 \pm \sqrt{5}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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